Numerically Applied
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Basic Circuit Laws
1. Ohm’s Law — V = IR
Solves for any one variable when the other two are known. Fundamental starting equation.
2. Power in Resistor — P = VI / I²R / V²R
Computes power using any available pair. Derived from Ohm’s law substitutions.
Inductors & Capacitors — Basic Relations
3. Inductor Voltage — v = L di/dt
Voltage induced by changing current. Provide numeric di/dt at the instant of interest.
4. Capacitor Current — i = C dv/dt
Current due to changing voltage across capacitor.
5. Energy in Inductor — w_L = ½ L I²
Magnetic energy stored. Often used with i_L(0) initial condition.
6. Energy in Capacitor — w_C = ½ C V²
Electric energy stored. Dual of inductor energy.
First-Order RC & RL Circuits — Natural & Step Responses
7. RC Time Constant — τ = RC
Governs speed of exponential transients in RC circuits.
8. RL Time Constant — τ = L/R
Governs speed of exponential transients in RL circuits.
9. RC Natural Response — v(t) = V₀ e^(-t/τ)
Source-free capacitor voltage decay (t ≥ 0). Vss = 0. Find V₀ from DC analysis at t=0−. Matches source sheet algorithm.
10. RC Step Response — v(t) = Vss + (V₀ − Vss) e^(-t/τ)
Complete response when DC source is applied. Find Vss (t→∞, cap open) and V₀ (t=0−) first per PDF 5-step method.
11. RL Natural Response — i(t) = I₀ e^(-(R/L)t)
Source-free inductor current decay. I₀ from t=0− (inductor current continuous).
12. RL Step Response — i(t) = Iss + (I₀ − Iss) e^(-(R/L)t)
Complete response for RL circuit with DC source. Iss found with inductor as short-circuit (t→∞).
Second-Order RLC Circuits — Parameters & Transient Response Forms
13. RLC Parameters — α, ω₀, Damping Type, Roots / ωd
First step for any RLC analysis. Computes Neper frequency α and resonant frequency ω₀. Classifies overdamped / critically damped / underdamped and gives s1,s2 or ωd. Use exact formulas from source sheet step 5.
14. Overdamped RLC Response — r(t) = rss + A₁e^{s₁t} + A₂e^{s₂t}
For α > ω₀. Supply A1/A2 (solved from initial conditions i_L(0), v_C(0) per PDF) and s1/s2 from Parameters calculator. rss usually 0 for natural response.
15. Critically Damped RLC Response — r(t) = rss + (A₁ + A₂ t) e^{-α t}
For α = ω₀ (repeated root). Form includes linear t multiplier. Obtain α from Parameters calculator.
16. Underdamped RLC Response — r(t) = rss + e^{-αt} (A₁ cos(ωd t) + A₂ sin(ωd t))
For α < ω₀ (ringing case). Most common. Supply ωd and α from Parameters calculator. A1/A2 from initial conditions.
Calculation Log — CSV Data Store
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